Valve and fluid control apparatus

ABSTRACT

A fluid control apparatus includes a piezoelectric pump and valve. The valve includes a second valve housing, second seal member, diaphragm, first seal member, and first valve housing and has a structure in which they are laminated in sequence. The first valve housing includes a second vent and third vent, has a valve seat, and includes six cavities. The second valve housing has a first vent and first vent and includes a valve seat and six first protrusions. The second valve housing further includes six second protrusions nearer the outer edges than the six first protrusions, as seen in the x-axis direction in plan view.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a Continuation of U.S. patent application Ser. No. 15/844,718filed on Dec. 18, 2017, which is a Continuation of U.S. patentapplication Ser. No. 14/948,528 filed on Nov. 23, 2015, which is aContinuation of International Patent Application No. PCT/JP2014/062771filed on May 14, 2014, which claims priority from Japanese PatentApplication No. 2013-109994 filed on May 24, 2013. The contents of theseapplications are incorporated herein by reference in their entireties.

BACKGROUND Technical Field

The present disclosure relates to a valve that prevents backflow of afluid and to a fluid control apparatus that includes the valve.

Patent Document 1 discloses a fluid control apparatus including a valve.

The fluid control apparatus includes a piezoelectric pump and the valve.By joining the upper surface of the piezoelectric pump to the bottomsurface of the valve, the valve is connected to the piezoelectric pump.

The valve has a cuff connection port that communicates with an arm bandrubber tube of a cuff. By fitting the arm band rubber tube of the cuffinto the cuff connection port in the valve, the fluid control apparatusis connected to the cuff.

The valve includes a second valve housing, a diaphragm made of arectangular thin film, and a first valve housing and has a structure inwhich they are laminated in sequence.

Patent Document 1: International Publication No. 2012-141113

BRIEF SUMMARY

The valve described in Patent Document 1 may preferably have sufficientsealing between the second valve housing and the diaphragm and betweenthe diaphragm and the first valve housing to prevent air from leakingfrom the inside of the valve.

After a study, the present inventor devised a valve having the structuredescribed below.

FIG. 10 is a cross-sectional view of a main portion of a fluid controlapparatus 900 according to a first comparative example. FIG. 11 is anexploded perspective view of a valve 901 illustrated in FIG. 10. FIG. 12is a cross-sectional view of a main portion of the valve 901 illustratedin FIG. 10. In FIGS. 11 and 12, a z-axis direction, y-axis direction,and x-axis direction are illustrated.

The details of each component will be provided below. The z-axisdirection indicates a direction in which members included in the valve901 are laminated. The x-axis direction indicates a direction in which acheck valve 160, a communication path 135, and an exhaust valve 170 arearranged. The y-axis direction indicates a direction perpendicular tothe z-axis direction and the x-axis direction.

As illustrated in FIGS. 10 and 11, the valve 901 includes a second valvehousing 192, a second seal member 952 made of a rectangular thin film, adiaphragm 920 made of a rectangular thin film, a first seal member 951made of a rectangular thin film, and a first valve housing 191 and has astructure in which they are laminated in sequence.

As illustrated in FIGS. 10 and 11, the first valve housing 191 has asecond vent 112 communicating with a cuff 109 and a third vent 113communicating with the outside of a fluid control apparatus 900,includes a valve seat 139 protruding from the surrounding area of thethird vent 113 toward the diaphragm 920, and has six cavities 182. Thevalve seat 139 has a cylindrical shape in which the third vent 113 ispresent in its central portion.

As illustrated in FIGS. 10 and 11, the bottom surface of the secondvalve housing 192 is bonded to the upper surface of a piezoelectric pump10. As illustrated in FIGS. 10 and 11, the second valve housing 192 hasa first vent 110 communicating with a discharge hole 56 in thepiezoelectric pump 10 and a first vent 111 communicating with adischarge hole 55 in the piezoelectric pump 10, includes a columnarvalve seat 138 protruding toward the diaphragm 920, and has six firstprotrusions 180 opposite the six cavities 182.

As illustrated in FIGS. 10 and 11, the diaphragm 920 has a circular holeportion 121 in the central portion in a region opposite the valve seat138. The diameter of the hole portion 121 is smaller than that of asurface of the valve seat 138 that is in contact with the diaphragm 920.

The diaphragm 920 is held between the first valve housing 191 and thesecond valve housing 192 and is fixed to the first valve housing 191 andthe second valve housing 192 such that it is in contact with the valveseat 139 and such that the surrounding area of the hole portion 121 isin contact with the valve seat 138. The valve seat 138 is disposed inthe second valve housing 192 such that it presses the surrounding areaof the hole portion 121 in the diaphragm 920.

Thus, the diaphragm 920 divides the inside of the first valve housing191 and the second valve housing 192. The diaphragm 920 constitutes thecheck valve 160 including a ring-shaped first lower valve room 131communicating with the first vent 111 and a columnar first upper valveroom 133 communicating with the second vent 112 with the communicationpath 135 disposed therebetween, together with the first valve housing191 and the second valve housing 192.

The diaphragm 920 also constitutes the exhaust valve 170 including acolumnar second lower valve room 132 communicating with the first vent110 and a ring-shaped second upper valve room 134 communicating with thefirst upper valve room 133 with the communication path 135 disposedtherebetween, together with the first valve housing 191 and the secondvalve housing 192. The above-described shape of each of the valve roomsis a shape seen in a direction perpendicular to the diaphragm 920 inplan view. The check valve 160, communication path 135, and exhaustvalve 170 are arranged along the x-axis direction.

The six cavities 182 in the first valve housing 191 are nearer the outeredges than the first lower valve room 131 and the second lower valveroom 132, as seen in the x-axis direction in plan view. Of the sixcavities 182, three cavities 182 are arranged along the x-axisdirection. The other three cavities 182 are located on the opposite sideto the previously described three cavities 182 such that the first lowervalve room 131 and the second lower valve room 132 are disposedtherebetween, and are arranged along the x-axis direction such that theyare parallel with the previously described three cavities 182.

The six first protrusions 180 in the second valve housing 192 are nearerthe outer edges than the first upper valve room 133 and the second uppervalve room 134, as seen in the x-axis direction in plan view. The sixfirst protrusions 180 are arranged opposite the six cavities 182.

The first seal member 951 has second through holes 156A to 156C in aregion that faces the first upper valve room 133, communication path135, and second upper valve room 134. The second through hole 156A mayhave a circular shape whose central axis is substantially coaxial withthat of the first upper valve room 133, for example. The second throughhole 156B may have a circular shape whose central axis is substantiallycoaxial with that of the second upper valve room 134, for example.

The second seal member 952 has first through holes 155A to 155B in aregion that faces the first lower valve room 131 and second lower valveroom 132. The first through hole 155A may have a circular shape whosecentral axis is substantially coaxial with that of the first lower valveroom 131, for example. The first through hole 155B may have a circularshape whose central axis is substantially coaxial with that of thesecond lower valve room 132, for example.

Next, a method for manufacturing the valve 901 is described. First, thesecond valve housing 192, second seal member 952, diaphragm 920, firstseal member 951, and first valve housing 191 are laminated, and the sixfirst protrusions 180 are fit into the six cavities 182. In this way,the diaphragm 920 is held between the first valve housing 191 and thesecond valve housing 192 with the first seal member 951 and the secondseal member 952 disposed therebetween.

Next, the multilayer body consisting of the second valve housing 192,second seal member 952, diaphragm 920, first seal member 951, and firstvalve housing 191 is placed on a stage S (see FIG. 12), and the endportions of the six first protrusions 180 are heat-staked. In this way,the end portions of the six first protrusions 180 are crushed, and thevalve 901 is obtained.

The valve 901 described above needs further reducing its cost. Inparticular, it is necessary to use a highly reliable material in thediaphragm 920, and this leads to one factor of a high manufacturing costof the valve 901.

The present inventor devised a valve 501 (see FIG. 13) including a firstseal member 151, a second seal member 152, and a diaphragm 120, in whichouter side portions J1 to J6 (see FIGS. 11 and 12) nearer the outeredges than the check valve 160 and the exhaust valve 170, as seen in thex-axis direction in plan view, and not directly contributing to thefunction as the valve are removed from the first seal member 951,diaphragm 920, and second seal member 952. The valve 501 has a reducedsize of the area used by the diaphragm 920 and aims to reduce themanufacturing cost of the valve 901.

However, as illustrated in FIG. 13, in the inner side portion withrespect to the first protrusions 180 in the valve 501, as seen in thex-axis direction, the first valve housing 191 and the second valvehousing 192 hold the diaphragm 120 therebetween with the first sealmember 151 and the second seal member 152 disposed therebetween. Incontrast, in the outer side portion with respect to the firstprotrusions 180, the first valve housing 191 and the second valvehousing 192 do not hold anything.

If the valve 501 is heat-staked as described above, the outer sideportion with respect to the first protrusions 180 in the first valvehousing 191 is warped toward the second valve housing 192, and the outerside portion with respect to the first protrusions 180 in the secondvalve housing 192 is warped toward the first valve housing 191.

Thus, the structure of the valve 501 has a problem in that leakage ofair from the inside of the valve 501 is large and the performance of thevalve 501 decreases.

As illustrated in FIG. 10, in the case of the fluid control apparatus900, in which the valve 901 is connected to the piezoelectric pump 10,warpage of the valve 901 affects warpage of the piezoelectric pump 10.Therefore, there is also a problem in that this may lead to a decreasein the performance of the piezoelectric pump 10.

The present disclosure provides a valve capable of reducing itsmanufacturing cost without necessarily decreasing the performance of thevalve, as compared with traditional valves and a fluid control apparatusincluding the valve.

The valve according to the present disclosure has a configurationdescribed below to solve the above problems.

(1) The valve includes a diaphragm having a hole portion,

a first seal member disposed on a first principal surface of thediaphragm,

a first valve housing joined to the diaphragm with the first seal memberdisposed therebetween, the first valve housing having a first hole, afirst valve room located near the first principal surface of thediaphragm and communicating with the first hole, and a plurality ofcavities located in an outer side portion with respect to the firstvalve room,

a second seal member disposed on a second principal surface of thediaphragm, and

a second valve housing joined to the diaphragm with the second sealmember disposed therebetween, the second valve housing having a secondhole and a second valve room located near the second principal surfaceof the diaphragm and communicating with the second hole, the secondvalve housing including a plurality of first protrusions located in theouter side portion with respect to the second valve room.

The diaphragm is held between the first valve housing and the secondvalve housing with the first seal member and the second seal memberdisposed therebetween by fitting the plurality of first protrusions intothe plurality of cavities,

a surrounding area of the hole portion in the diaphragm is in contactwith the second valve housing in the second valve room, and the holeportion is covered therewith,

each of the first seal member, the diaphragm, and the second seal memberhas a circumference smaller than a circumference of each of the firstvalve housing and the second valve housing and is disposed in an innerside portion with respect to the plurality of first protrusions, and

at least one of the first valve housing and the second valve housingincludes a plurality of second protrusions located in the outer sideportion with respect to the plurality of first protrusions.

The valve of this configuration has the structure in which the firstvalve housing, first seal member, diaphragm, second seal member, andsecond valve housing are laminated. In this configuration, thecircumference of the diaphragm is smaller than that of each of the firstvalve housing and the second valve housing and is disposed in the innerside portion with respect to the plurality of first protrusions. Thus,this configuration can have a smaller size of the area used by thediaphragm, as compared with the valve 901 (see FIG. 11) according to thefirst comparative example, which has the structure in which thecircumference of the diaphragm is the same as that of each of the firstvalve housing and the second valve housing.

In the valve of this configuration, in the inner side portion withrespect to the first protrusions, as seen in the x-axis direction inplan view, the first valve housing and the second valve housing hold thediaphragm therebetween with the first seal member and the second sealmember disposed therebetween. In contrast, in the outer side portionwith respect to the first protrusions, as seen in the x-axis directionin plan view, the plurality of second protrusions are located betweenthe first valve housing and the second valve housing.

Thus, when the multilayer body consisting of the first valve housing,first seal member, diaphragm, second seal member, and second valvehousing is placed on the stage and the end portions of the plurality offirst protrusions are heat-stacked, the plurality of second protrusionscome into contact with the first valve housing or second valve housing,and warpage of the outer side portion with respect to the firstprotrusions in the first valve housing and second valve housing can besuppressed. That is, this configuration can suppress leakage of air fromthe inside of the valve.

Consequently, according to this configuration, the manufacturing cost ofthe valve can be reduced without necessarily decreasing the performanceof the valve, as compared with traditional valves.

(2) Each of the plurality of second protrusions may have a heightsmaller than a height of each of the plurality of first protrusions.

In this configuration, the end portions of the plurality of firstprotrusions, which protrude toward the second valve housing further thanthe plurality of second protrusions, are heat-staked.

(3) The height of each of the plurality of second protrusions may beequal to a sum of a thickness of the first seal member and a thicknessof the second seal member.

In this configuration, the plurality of second protrusions, each havingthe same height as the sum of the thickness of the first seal member andthat of the second seal member, are located between the outer sideportion with respect to the first protrusions in the first valve housingand the outer side portion with respect to the first protrusions in thesecond valve housing.

Thus, when the end portions of the plurality of first protrusions areheat-staked as described above, because the plurality of secondprotrusions come into contact with the first valve housing or secondvalve housing, warpage of the outer side portions with respect to thefirst protrusions in the first valve housing and in the second valvehousing can be further suppressed. That is, this configuration canfurther suppress leakage of air from the inside of the valve.

Consequently, according to this configuration, the manufacturing cost ofthe valve can be reduced without necessarily decreasing the performanceof the valve, as compared with traditional valves.

The fluid control apparatus according to the present disclosure has aconfiguration described below to solve the above problems.

(4) The fluid control apparatus includes a pump having a discharge hole,and

the valve according to any one of the above-described (1) to (3).

The first hole in the first valve housing is connected to a fluidstorage portion that stores fluid, and

the second hole in the second valve housing is connected to thedischarge hole in the pump.

By using the valve in any one of the above-described (1) to (3), thefluid control apparatus including that valve can achieve substantiallythe same advantages.

According to the present disclosure, the manufacturing cost of the valvecan be reduced without necessarily decreasing the performance of thevalve, as compared with traditional valves.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a main portion of a fluid controlapparatus 100 according to an embodiment of the present disclosure.

FIG. 2 is an exploded perspective view of a piezoelectric pump 10illustrated in FIG. 1.

FIG. 3 is an exploded perspective view of a valve 101 illustrated inFIG. 1.

FIG. 4 is an exploded perspective view of the valve 101 illustrated inFIG. 1.

FIG. 5 is a bottom view of a second valve housing 192 included in thevalve 101 illustrated in FIG. 1.

FIG. 6 is a cross-sectional view of a main portion of the valve 101illustrated in FIG. 1.

FIG. 7 is an illustration for describing air streams in the fluidcontrol apparatus 100 while the piezoelectric pump 10 illustrated inFIG. 1 is driven.

FIG. 8 is an illustration for describing air streams in the fluidcontrol apparatus 100 immediately after the piezoelectric pump 10illustrated in FIG. 1 stops being driven.

FIG. 9 illustrates a relationship between the position in a second valvehousing 192 and the amount of warpage of the second valve housing 192 inthe valve 101 according to the embodiment of the present disclosure, ina valve 901 according to a first comparative example, and in a valve 501according to a second comparative example.

FIG. 10 is a cross-sectional view of a main portion of a fluid controlapparatus 900 according to the first comparative example.

FIG. 11 is an exploded perspective view of the valve 901 illustrated inFIG. 10.

FIG. 12 is a cross-sectional view of a main portion of the valve 901illustrated in FIG. 10.

FIG. 13 is a cross-sectional view of a main portion of the valve 501before the valve 501 is heat-staked according to the second comparativeexample.

DESCRIPTION OF EMBODIMENTS

A fluid control apparatus 100 according to an embodiment of the presentdisclosure is described below.

FIG. 1 is a cross-sectional view of a main portion of the fluid controlapparatus 100 according to the embodiment of the present disclosure. Thefluid control apparatus 100 includes a piezoelectric pump 10 and a valve101. The fluid control apparatus 100 is an apparatus for measuring bloodpressure of a subject. By joining the upper surface of the piezoelectricpump 10 to the bottom surface of the valve 101, the valve 101 isconnected to the piezoelectric pump 10.

The valve 101 has a cuff connection port 106A communicating with an armband rubber tube 109A of a cuff 109. By fitting the arm band rubber tube109A of the cuff 109 into the cuff connection port 106A in the valve101, the fluid control apparatus 100 is connected to the cuff 109.

The cuff 109 corresponds to “fluid storage portion” in the presentdisclosure.

The structure of each of the piezoelectric pump 10 and the valve 101 isdescribed. First, the structure of the piezoelectric pump 10 isdescribed with reference to FIGS. 1 and 2.

FIG. 2 is an exploded perspective view of the piezoelectric pump 10illustrated in FIG. 1. The piezoelectric pump 10 includes a base 91, aflexible plate 51, a spacer 53A, a strengthening plate 43, a vibratingplate unit 60, a piezoelectric element 42, a spacer 53B, an electrodeconduction plate 70, a spacer 53C, and a lid plate 54 and has astructure in which they are laminated in sequence.

The base 91, flexible plate 51, spacer 53A, part of the vibrating plateunit 60, spacer 53B, electrode conduction plate 70, spacer 53C, and lidplate 54 constitute a pump housing 80. The inner space of the pumphousing 80 corresponds to a pump room 45.

The vibrating plate unit 60 includes a vibrating plate 41, a frame plate61, coupling portions 62, and an external terminal 63. The vibratingplate unit 60 is formed by punching on a metal plate.

The frame plate 61 is disposed on the periphery of the vibrating plate41. The external terminal 63 for electric connection is disposed on theframe plate 61. The vibrating plate 41 is coupled to the frame plate 61by the coupling portions 62. The coupling portions 62 may have a thinring shape. The coupling portions 62 have an elastic structure havingelasticity of a small spring constant.

Accordingly, the vibrating plate 41 is elastically supported on theframe plate 61 at two points with flexibility by the two couplingportions 62. Thus, bending vibration of the vibrating plate 41 is notsubstantially hindered. That is, the peripheral portion (of course,central portion) of a piezoelectric actuator 40 is not virtuallyrestrained.

In the example illustrated in FIG. 2, the coupling portions 62 aredisposed at two points. The coupling portions 62 may also be disposed atthree points. The coupling portions 62 do not interfere with vibrationof the piezoelectric actuator 40, but have an effect on vibration of thepiezoelectric actuator 40 to some degree. Thus, if the three couplingportions 62 are used, for example, the vibrating plate 41 can besupported more naturally and cracking of the piezoelectric element 42can also be prevented.

The piezoelectric element 42 is disposed on the upper surface of thedisc-shaped vibrating plate 41. The strengthening plate 43 is disposedon the lower surface of the vibrating plate 41. The vibrating plate 41,piezoelectric element 42, and strengthening plate 43 constitute thedisc-shaped piezoelectric actuator 40. The piezoelectric element 42 maybe made of a PZT-based ceramic material, for example.

The vibrating plate 41 may also be made of a metal plate having acoefficient of linear expansion larger than that of each of thepiezoelectric element 42 and the strengthening plate 43, and it may bethermoset at the time of bonding. This can avoid warpage of the wholepiezoelectric actuator 40, enable appropriate compressive stress toremain in the piezoelectric element 42, and prevent cracking of thepiezoelectric element 42.

For example, the vibrating plate 41 may be made of a material having alarge coefficient of linear expansion, such as phosphor bronze (C5210)or stainless steel SUS301, and the strengthening plate 43 may be made of42 nickel, 36 nickel, or stainless steel SUS430.

For the vibrating plate 41, piezoelectric element 42, and strengtheningplate 43, the arrangement in which the piezoelectric element 42,strengthening plate 43, and vibrating plate 41 are positioned in thisorder from above may also be used. In this case, the coefficient oflinear expansion is also adjusted by setting the materials of thestrengthening plate 43 and vibrating plate 41 to enable appropriatecompressive stress to remain in the piezoelectric element 42.

The spacer 53B is disposed on the upper surface of the frame plate 61.The spacer 53B is made of resin. The thickness of the spacer 53B is thesame as or slightly larger than that of the piezoelectric element 42.The frame plate 61 electrically insulates the electrode conduction plate70 and the vibrating plate unit 60.

The electrode conduction plate 70 is disposed on the upper surface ofthe spacer 53B. The electrode conduction plate 70 is made of metal. Theelectrode conduction plate 70 includes a frame member 71 that openssubstantially circularly, an internal terminal 73 protruding into thisopened space, and an external terminal 72 protruding toward the outside.

The end of the internal terminal 73 is joined to the surface of thepiezoelectric element 42 by soldering. By setting the location of thesoldered joint as the location corresponding to a node of bendingvibration of the piezoelectric actuator 40, vibration of the internalterminal 73 is suppressed.

The spacer 53C is disposed on the upper surface of the electrodeconduction plate 70. The spacer 53C is made of resin. The spacer 53C hasa thickness similar to that of the piezoelectric element 42. The spacer53C is a spacer for preventing the solder portion in the internalterminal 73 from coming into contact with the lid plate 54 when thepiezoelectric actuator 40 vibrates. The spacer 53C also prevents adecrease in vibration amplitude caused by air resistance produced by thesurface of the piezoelectric element 42 excessively getting close to thelid plate 54. Thus, the thickness of the spacer 53C may be similar tothat of the piezoelectric element 42.

The lid plate 54 is disposed on the upper surface of the spacer 53C. Thelid plate 54 has discharge holes 55 and 56. The lid plate 54 covers theupper portion of the piezoelectric actuator 40.

The spacer 53A is disposed on the lower surface of the vibrating plateunit 60. That is, the spacer 53A is disposed between the upper surfaceof the flexible plate 51 and the lower surface of the vibrating plateunit 60. The spacer 53A has a thickness in which approximately severaltens of micrometers is added to the thickness of the strengthening plate43. The spacer 53A is a spacer for preventing the piezoelectric actuator40 from coming into contact with the flexible plate 51 when thepiezoelectric actuator 40 vibrates.

The flexible plate 51 is disposed on the lower surface of the spacer53A. The flexible plate 51 has a suction hole 52 in its center.

The base 91 is disposed on the lower surface of the flexible plate 51.The base 91 has a columnar cavity 92 in its central portion. Theflexible plate 51 includes a fixed portion 57 fixed to the base 91 and amovable portion 58 nearer the center than the fixed portion 57 andfacing the cavity 92.

The movable portion 58 can vibrate at substantially the same frequencyas that for the piezoelectric actuator 40 due to pressure changes in airproduced by vibration of the piezoelectric actuator 40. The naturalfrequency of the movable portion 58 is designed to be the same as orslightly lower than the driving frequency of the piezoelectric actuator40.

When the vibration of the flexible plate 51 is designed to have a phasethat lags the phase of vibration of the piezoelectric actuator 40 (forexample, with a lag of 90 degrees), changes in thickness of the gapbetween the flexible plate 51 and the piezoelectric actuator 40substantially increase.

Accordingly, when an alternating driving voltage is applied to theexternal terminals 63 and 72, the piezoelectric actuator 40 bends andvibrates concentrically. In addition, the movable portion 58 in theflexible plate 51 also vibrates together with the vibration of thepiezoelectric actuator 40. In this way, the piezoelectric pump 10 sucksair into the pump room 45 through the cavity 92 and the suction hole 52.Additionally, the piezoelectric pump 10 discharges air from the pumproom 45 through the discharge holes 55 and 56.

At this time, the peripheral portion of the piezoelectric actuator 40 inthe piezoelectric pump 10 is not substantially fixed. Thus, according tothe piezoelectric pump 10, the loss involving with vibration of thepiezoelectric actuator 40 is small, and a high discharge pressure and alarge discharge flow quantity are obtainable while the piezoelectricpump 10 keeps its small size and low profile.

Next, the structure of the valve 101 is described with reference toFIGS. 1 and 3 to 6.

FIGS. 3 and 4 are exploded perspective views of the valve 101illustrated in FIG. 1. FIG. 3 is an exploded perspective view of thevalve 101 seen from the upper surface side where it is connected to thecuff 109. FIG. 4 is an exploded perspective view of the valve 101 seenfrom the bottom surface side where it is joined to the piezoelectricpump 10. FIG. 5 is a bottom view of a second valve housing 192 includedin the valve 101 illustrated in FIG. 1. FIG. 6 is a cross-sectional viewof a main portion of the valve 101 illustrated in FIG. 1.

In FIGS. 3, 5, and 6, a z-axis direction, y-axis direction, and x-axisdirection are illustrated. The z-axis direction indicates a direction inwhich the members included in the valve 101 are laminated. The x-axisdirection indicates a direction in which a check valve 160, acommunication path 135, and an exhaust valve 170 are arranged. They-axis direction indicates a direction perpendicular to the z-axisdirection and x-axis direction.

A “first hole” in the present disclosure corresponds to a second vent112. A “second hole” in the present disclosure corresponds to firstvents 110 and 111. A “first valve room” in the present disclosurecorresponds to a first upper valve room 133 and a second upper valveroom 134. A “second valve room” in the present disclosure corresponds toa first lower valve room 131 and a second lower valve room 132.

As illustrated in FIGS. 1, 3, 4, and 5, the valve 101 includes a secondvalve housing 192, a second seal member 152 made of a rectangular thinfilm, a diaphragm 120 made of a rectangular thin film, a first sealmember 151 made of a rectangular thin film, and a first valve housing191 and has a structure in which they are laminated in sequence.

As illustrated in FIGS. 1, 3, and 4, the first valve housing 191 has asecond vent 112 communicating with the cuff 109, a third vent 113communicating with the outside of the fluid control apparatus 100,includes a valve seat 139 protruding from the surrounding area of thethird vent 113 toward the diaphragm 120, and has six cavities 182. Thefirst valve housing 191 may be made of resin, for example. The valveseat 139 has a cylindrical shape having the third vent 113 in itscentral portion.

The six cavities 182 in the first valve housing 191 are nearer the outeredges than the first lower valve room 131 and the second lower valveroom 132, which are described below, as seen in the x-axis direction inplan view. Of the six cavities 182, three cavities 182 are arrangedalong the x-axis direction. The other three cavities 182 are located onthe opposite side to the previously described three cavities 182 suchthat the first lower valve room 131 and the second lower valve room 132are disposed therebetween, and are arranged along the x-axis directionsuch that they are parallel with the previously described three cavities182.

As illustrated in FIG. 1, the bottom surface of the second valve housing192 is bonded to the upper surface of the piezoelectric pump 10. Asillustrated in FIGS. 1, 3, 4, and 5, the second valve housing 192 hasthe first vent 110 communicating with the discharge hole 56 in thepiezoelectric pump 10, the first vent 111 communicating with thedischarge hole 55 in the piezoelectric pump 10, includes a columnarvalve seat 138 protruding toward the diaphragm 120, and has six firstprotrusions 180 opposite the six cavities 182. The second valve housing192 may be made of resin, for example. The six first protrusions 180 inthe second valve housing 192 are nearer the outer edges than the firstupper valve room 133 and the second upper valve room 134, which aredescribed below, as seen in the x-axis direction in plan view.

The second valve housing 192 further includes six second protrusions 181nearer the outer edges than the six first protrusions 180, as seen inthe x-axis direction in plan view.

In the state where the six first protrusions 180 are fit in the sixcavities 182, the six second protrusions 181 are nearer the outer edgesthan the first seal member 151, diaphragm 120, and second seal member152, as seen in the x-axis direction in plan view.

As illustrated in FIGS. 1, 3, and 4, the diaphragm 120 has a circularhole portion 121 in the central portion in a region opposite the valveseat 138. The diameter of the hole portion 121 is smaller than that of asurface of the valve seat 138 that is in contact with the diaphragm 120.The circumference of the diaphragm 120 is smaller than that of each ofthe first valve housing 191 and the second valve housing 192. Thediaphragm 120 may be made of rubber, such as ethylene propylene dienerubber (EPDM) or silicone, for example.

By fitting the six first protrusions 180 into the six cavities 182, thediaphragm 120 is held between the first valve housing 191 and the secondvalve housing 192 with the first seal member 151 and second seal member152 disposed therebetween.

Thus, as illustrated in FIG. 6, the diaphragm 120 covers the inner sideregion in the first valve housing 191 with respect to the six cavities182, as seen in the x-axis direction in plan view, and the inner sideregion in the second valve housing 192 with respect to the six firstprotrusions 180, as seen in the x-axis direction in plan view, and is incontact with the valve seat 138, and the surrounding area of the holeportion 121 is in contact with the valve seat 138. The valve seat 138 isdisposed in the second valve housing 192 such that it presses thesurrounding area of the hole portion 121 in the diaphragm 120.

The diaphragm 120 divides the inside of the first valve housing 191 andthe second valve housing 192. The diaphragm 120 constitutes the checkvalve 160 including the ring-shaped first lower valve room 131communicating with the first vent 111 and the columnar first upper valveroom 133 communicating with the second vent 112 with the communicationpath 135 disposed therebetween, together with the first valve housing191 and the second valve housing 192.

The diaphragm 120 also constitutes the exhaust valve 170 including thecolumnar second lower valve room 132 communicating with the first vent110 and the ring-shaped second upper valve room 134 communicating withthe first upper valve room 133 with the communication path 135 disposedtherebetween, together with the first valve housing 191 and the secondvalve housing 192.

The above-described shape of each of the valve rooms is a shape seen ina direction perpendicular to the diaphragm 120 in plan view. The checkvalve 160, communication path 135, and exhaust valve 170 are arrangedalong the x-axis direction.

One example of the diameter of each of the first lower valve room 131,second lower valve room 132, first upper valve room 133, and secondupper valve room 134 may be 7.0 mm. One example of the diameter of thesurface of the valve seat 138 in contact with the diaphragm 120 may be1.5 mm.

The first seal member 151 has second through holes 156A to 156C in aregion that faces the first upper valve room 133, communication path135, and second upper valve room 134. The second through hole 156A mayhave a circular shape whose central axis is substantially coaxial withthat of the first upper valve room 133, for example. The second throughhole 156B may have a circular shape whose central axis is substantiallycoaxial with that of the second upper valve room 134, for example.

One example of the diameter of each of the second through holes 156A and156B may be 6.6 mm. That is, the circumference of the first seal member151 is smaller than that of each of the first valve housing 191 and thesecond valve housing 192. The first seal member 151 may be made ofdouble-sided tape or adhesive, for example.

The second seal member 152 has first through holes 155A and 155B in aregion that faces the first lower valve room 131 and second lower valveroom 132. The first through hole 155A may have a circular shape whosecentral axis is substantially coaxial with that of the first lower valveroom 131, for example. The first through hole 155B may have a circularshape whose central axis is substantially coaxial with that of thesecond lower valve room 132, for example.

One example of the diameter of each of the first through holes 155A and155B may be 6.6 mm. That is, the circumference of the second seal member152 is smaller than that of each of the first valve housing 191 and thesecond valve housing 192. The second seal member 152 may be made ofdouble-sided tape or adhesive, for example.

The diameter of the first through hole 155A is larger than that of thevalve seat 138 and smaller than that of the first lower valve room 131.That is, the circumference of the first through hole 155A is larger thanthat of the valve seat 138 and smaller than that of the first lowervalve room 131. Similarly, the diameter of the first through hole 155Bis smaller than that of the second lower valve room 132. That is, thecircumference of the first through hole 155B is smaller than that of thesecond lower valve room 132.

As described above, part of the first seal member 151 is located insidethe first upper valve room 133 and the second upper valve room 134 inthe valve 101. Similarly, part of the second seal member 152 is locatedinside the first lower valve room 131 and the second lower valve room132. As illustrated in FIG. 1, the valve 101 includes the check valve160 and the exhaust valve 170.

First, the check valve 160 includes part of the second valve housing 192that has the first vent 111, part of the first valve housing 191 thathas the second vent 112, the surrounding area of the hole portion 121 inthe diaphragm 120, and the valve seat 138 being in contact with thatsurrounding area and covering the hole portion 121. The check valve 160allows fluid to flow from the first lower valve room 131 toward thefirst upper valve room 133 and blocks fluid from flowing from the firstupper valve room 133 toward the first lower valve room 131.

In the check valve 160, the diaphragm 120 comes into contact with orbecomes separated from the valve seat 138 in accordance with adifference between the pressure in the first lower valve room 131 andthat in the first upper valve room 133.

Next, the exhaust valve 170 includes part of the second valve housing192 that has the first vent 110, part of the first valve housing 191that has the second vent 112 and the third vent 113, part of thediaphragm 120, and the valve seat 139 protruding from the surroundingarea of the third vent 113 toward the diaphragm 120, being in contactwith the diaphragm 120, and being covered therewith.

In the exhaust valve 170, the diaphragm 120 comes into contact with orbecomes separated from the valve seat 139 in accordance with adifference between the pressure in the second lower valve room 132 andthat in the second upper valve room 134.

Next, a method for manufacturing the valve 101 is described. First, thesecond valve housing 192, second seal member 152, diaphragm 120, firstseal member 151, and first valve housing 191 are laminated, and the sixfirst protrusions 180 are fit into the six cavities 182. In this way,the diaphragm 120 is held between the first valve housing 191 and thesecond valve housing 192 with the first seal member 151 and the secondseal member 152 disposed therebetween.

Next, the multilayer body consisting of the second valve housing 192,second seal member 152, diaphragm 120, first seal member 151, and firstvalve housing 191 is placed on a stage S (see FIG. 6), and the endportions of the six first protrusions 180 are heat-staked. In this way,the end portions of the six first protrusions 180 are crushed, and thevalve 101 illustrated in FIG. 6 is obtained.

As illustrated in FIG. 6, in the inner side portion with respect to thefirst protrusions 180 in the valve 101, as seen in the x-axis directionin plan view, the first valve housing 191 and the second valve housing192 hold the diaphragm 120 with the first seal member 151 and the secondseal member 152 disposed therebetween. In contrast, in the outer sideportion with respect to the first protrusions 180, the six secondprotrusions 181 are disposed.

Thus, when the multilayer body consisting of the first valve housing191, first seal member 151, diaphragm 120, second seal member 152, andsecond valve housing 192 is placed on the stage S and the end portionsof the six first protrusions 180 are heat-staked, because the outer sideportion with respect to the first protrusions 180 in the first valvehousing 191 is in contact with the six second protrusions 181, warpageof the outer side portion with respect to the first protrusions 180 inthe first valve housing 191 toward the second valve housing 192 can besuppressed and warpage of the outer side portion with respect to thefirst protrusions 180 in the second valve housing 192 toward the firstvalve housing 191 can be suppressed. That is, in the present embodiment,leakage of air from the inside of the valve 101 can be suppressed.

Consequently, according to the present embodiment, the manufacturingcost of the valve 101 can be reduced without necessarily decreasing theperformance of the valve, as compared with traditional valves.

The height of each of the six second protrusions 181 may be equal to thesum of the thickness of the first seal member 151, that of the diaphragm120, and that of the second seal member 152. In this case, the sixsecond protrusions 181, each having the same height as the sum of thethickness of the first seal member 151, that of the diaphragm 120, andthat of the second seal member 152, are located between the outer sideportion with respect to the first protrusions 180 in the first valvehousing 191 and the outer side portion with respect to the firstprotrusions 180 in the second valve housing 192.

Thus, when the end portions of the six first protrusions 180 areheat-staked as described above, because the outer side portion withrespect to the first protrusions 180 in the first valve housing 191 isin contact with the six second protrusions 181, warpage of the outerside portions with respect to the first protrusions 180 in the firstvalve housing 191 and in the second valve housing 192 can be furthersuppressed. That is, leakage of air from the inside of the valve 101 canbe further suppressed.

Next, operations of the fluid control apparatus 100 during bloodpressure measurement are described.

FIG. 7 is an illustration for describing air streams in the fluidcontrol apparatus 100 while the piezoelectric pump 10 illustrated inFIG. 1 is driven.

To start measuring a blood pressure, the fluid control apparatus 100first drives the piezoelectric pump 10. When the piezoelectric pump 10is driven, air is first sucked into the pump room 45 in thepiezoelectric pump 10 through the cavity 92 and the suction hole 52.Then, the air is discharged through the ports 55 and 56 and flows intoboth the second lower valve room 132 and the first lower valve room 131in the valve 101.

In this way, in the exhaust valve 170, the pressure in the second lowervalve room 132 is higher than that in the second upper valve room 134.Thus, as illustrated in FIG. 7, the diaphragm 120 seals the third vent113 and blocks passage of air between the second vent 112 and the thirdvent 113.

In the check valve 160, the pressure in the first lower valve room 131is higher than that in the first upper valve room 133. Thus, thesurrounding area of the hole portion 121 in the diaphragm 120 becomesseparated from the valve seat 138, and the first vent 111 and the secondvent 112 communicate with each other through the hole portion 121.

Therefore, air is sent from the piezoelectric pump 10 to the cuff 109through the first vent 111, hole portion 121, and second vent 112 in thevalve 101 (see FIG. 7), and the pressure in the cuff 109 (air pressure)is increased.

The diaphragm 120 is fixed to the first valve housing 191 and the secondvalve housing 192 such that the surrounding area of the hole portion 121in the diaphragm 120 is in contact with the valve seat 138. The valveseat 138 presses the surrounding area of the hole portion 121 in thediaphragm 120.

In this way, the air flowing out of the hole portion 121 through thefirst vent 111 in the valve 101 flows from the hole portion 121 into thefirst upper valve room 133 and the second upper valve room 134 with apressure slightly lower than the discharge pressure of the piezoelectricpump 10. The discharge pressure of the piezoelectric pump 10 is appliedto the second lower valve room 132.

Therefore, in the valve 101, the pressure in the second lower valve room132 is slightly higher than that in the second upper valve room 134, andthe state in which the diaphragm 120 seals the third vent 113 and opensthe hole portion 121 is maintained.

As illustrated in FIGS. 3 and 4, because each of the valve rooms 131,132, 133, and 134 in the valve 101 has a circular outer shape, tensionis evenly applied to the diaphragm 120 (in particular, adjacent regionof the surrounding area of the hole portion 121).

Thus, the occurrence of states where the hole portion 121 in thediaphragm 120 is inclined with respect to the valve seat 138 when thediaphragm 120 comes into contact therewith and the occurrence of stateswhere the hole portion 121 in the diaphragm 120 is displaced in ahorizontal direction with respect to the valve seat 138 can besuppressed. Consequently, according to the valve 101, each of the valveelements can be smoothly opened and closed.

FIG. 8 is an illustration for describing air streams in the fluidcontrol apparatus 100 immediately after the piezoelectric pump 10illustrated in FIG. 1 stops being driven.

When measurement of the blood pressure is completed, the fluid controlapparatus 100 stops driving the piezoelectric pump 10. When thepiezoelectric pump 10 stops being driven, air in the pump room 45, firstlower valve room 131, and second lower valve room 132 is quickly ejectedfrom the suction hole 52 and cavity 92 to the outside of the fluidcontrol apparatus 100. The pressure in the cuff 109 is applied to thefirst upper valve room 133 and the second upper valve room 134 throughthe second vent 112.

Therefore, in the check valve 160, the pressure in the first lower valveroom 131 becomes lower than the pressure in the first upper valve room133. The diaphragm 120 comes into contact with the valve seat 138 andseals the hole portion 121.

In the exhaust valve 170, the pressure in the second lower valve room132 becomes lower than the pressure in the second upper valve room 134.The diaphragm 120 becomes separated from the valve seat 139 and opensthe third vent 113.

That is, in the valve 101, the second vent 112 and the third vent 113communicate with each other through the communication path 135 and thesecond upper valve room 134. Thus, air in the cuff 109 is quicklyejected from the third vent 113 through the second vent 112,communication path 135, and second upper valve room 134 (see FIG. 8).

Consequently, according to the valve 101 in the present embodiment,after compressed air is charged into the cuff 109, the air can bequickly ejected from the cuff 109.

As previously described, in the valve 101, part of the second sealmember 152 is located inside the first lower valve room 131 and thesecond lower valve room 132, and part of the first seal member 151 islocated inside the first upper valve room 133 and the second upper valveroom 134.

Thus, the first seal member 151 and the second seal member 152 can bondthe first valve housing 191, the second valve housing 192, and thediaphragm 120 and can capture foreign matter present inside each of thevalve rooms 131, 132, 133, and 134.

Consequently, according to the valve 101, if foreign matter enters thevalve 101, for example, malfunction caused by the foreign matter can besuppressed. In particular, in the exhaust valve 170, blockage of thethird vent 113 in the valve seat 139 by the foreign matter can besuppressed.

The fluid control apparatus 100 including the valve 101 in the presentembodiment can achieve substantially the same advantages.

The performance of the valve 101 can be expressed by a pressure loss anda leak pressure. In particular, air leakage from the first vents 110 and111 to the third vent 113 in the valve 101 while the piezoelectric pump10 is driven materially affects the performance of the valve 101.

The pressure loss is a loss occurring when the check valve 160 isbrought into an open state. Tension is applied to the diaphragm 120, andthe valve seat 138 is disposed in the second valve housing 192 so as topress the surrounding area of the hole portion 121 in the diaphragm 120.That is, a stress from the first upper valve room 133 toward the firstlower valve room 131 is applied to the diaphragm 120.

Thus, when the check valve 160 is brought into an open state, a pressureP2 in the first upper valve room 133 becomes lower than a pressure P1 inthe first lower valve room 131 by the amount corresponding to theabove-described stress. The pressure loss can be calculated from theexpression “pressure loss =pressure P1 in first lower valve room131—pressure P2 in first upper valve room 133.”

Due to this pressure loss, a force for bringing the exhaust valve 170into a closed state (force that presses the diaphragm 120 to the valveseat 139 from the side of the second lower valve room 132) iscontinuously applied to the exhaust valve 170 while air is sent from thefirst vent 111 in the valve 101 to the cuff 109. Thus, the exhaust valve170 is brought into the closed state.

If the pressure loss is small, the difference between the pressure P2 inthe first upper valve room 133 and the pressure P1 in the first lowervalve room 131 is small. That is, the force for bringing the exhaustvalve 170 into the closed state (force that presses the diaphragm 120 tothe valve seat 139 from the side of the second lower valve room 132)reduces, and air leakage from the first vents 110 and 111 to the thirdvent 113 in the valve 101 increases.

If the leakage is large, efficiency in charging air from the first vent111 in the valve 101 into the cuff 109 deceases. The valve 101suppresses leakage of air from the cuff 109 through the third vent 113by using the pressure loss caused by the tension of the diaphragm 120.

The leak pressure can be calculated from the expression “leakpressure=pressure in cuff 109 while piezoelectric pump 10 isdriven—pressure in cuff 109 five seconds after piezoelectric pump 10stops being driven.”

Comparison among the valve 101 (see FIG. 1) according to the embodimentof the present disclosure, the valve 901 (see FIG. 12) according to thefirst comparative example, and the valve 501 (see FIG. 13) according tothe second comparative example is described below.

As previously explained, the valve 501 differs from the valve 901 inthat it includes the first seal member 151, second seal member 152, anddiaphragm 120, in which the outer side portions J1 to J6 (see FIGS. 12and 13) nearer the outer edges than the check valve 160 and the exhaustvalve 170, as seen in the x-axis direction in plan view, are removedfrom the first seal member 951, diaphragm 920, and second seal member952. The valve 101 differs from the valve 501 in that it includes thesecond protrusions 181.

FIG. 9 illustrates a relationship between the position in the secondvalve housing 192 and the amount of warpage of the second valve housing192 in the valve 101 according to the embodiment of the presentdisclosure, in the valve 901 according to the first comparative example,and in the valve 501 according to the second comparative example. FIG. 9illustrates results of measurement of the amount of warpage from point Athrough point B to point C in the second valve housing 192 in valve 101,valve 901, and valve 501 by using a laser displacement gage.

As illustrated in FIG. 5, the points A and C are located in an outerside portion with respect to the first protrusions 180 in the secondvalve housing 192, and the point B is located in an inner side portionwith respect to the first protrusions 180 in the second valve housing192.

Next, results of measurement by driving the piezoelectric pump 10 andapplying discharge pressure 40 kPa of the piezoelectric pump 10 to thevalves 101, 501, and 901, and measuring a pressure loss and leakpressure in the valves 101, 501, and 901 are listed in Table 1.

TABLE 1 Pressure Loss [kPa] Leak Pressure [kPa] Valve 101 0.7 0.1 Valve501 0.1 1.1 Valve 901 0.7 0.1

The experiment reveals that the pressure loss in the valve 501 is 0.1kPa and the pressure loss in each of the valves 101 and 901 is 0.7 kPaand that the leak pressure in the valve 501 is 1.1 kPa and the leakpressure in each of the valves 101 and 901 is 0.1 kPa.

Possible reasons for the above results are described below. For thevalve 501, when the multilayer body consisting of the first valvehousing 191, first seal member 151, diaphragm 120, second seal member152, and second valve housing 192 is placed on the stage S and the endportions of the six first protrusions 180 are heat-staked, the outerside portion with respect to the first protrusions 180 in the firstvalve housing 191 is warped toward the second valve housing 192. Thus,for the valve 501, sufficient tension of the diaphragm 120 is notobtainable, that is, a pressure loss equivalent to that in the valve 901does not occur, and the leak pressure is higher than that in the valves101 and 901.

In contrast, for the valve 101, when the multilayer body is placed onthe stage S and the end portions of the six first protrusions 180 areheat-staked, the outer side portion with respect to the firstprotrusions 180 in the first valve housing 191 comes into contact withthe six second protrusions 181 and warpage can be suppressed. Thus, forthe valve 101, sufficient tension of the diaphragm 120 is obtainable,that is, a pressure loss equivalent to that in the valve 901 occurs, andair leakage from the inside of the valve 101 can be suppressed.

Consequently, according to the valve 101 in the present embodiment, themanufacturing cost of the valve 101 can be reduced without necessarilydecreasing the performance of the valve, as compared with traditionalvalves.

Other Embodiments

In the foregoing embodiment, air is used as the fluid. Other forms canalso be used. Gas other than air can also be used as the fluid.

The pump in the foregoing embodiment includes the piezoelectric actuator40, which bends and vibrates in a unimorph manner. The pump may alsoinclude an actuator that includes piezoelectric elements attached toboth surfaces of a vibrating plate and bends and vibrates in a bimorphmanner.

The pump in the foregoing embodiment includes the piezoelectric actuator40, which bends and vibrates due to expansion and contraction of thepiezoelectric element 42. Other forms may also be used. For example, thepump may include an actuator that bends and vibrates by electromagneticdriving.

In the foregoing embodiment, the piezoelectric element is made of aPZT-based ceramic material. Other forms may also be used. For example,the piezoelectric element may be made of a lead-free piezoelectricceramic material, such as a potassium sodium niobate-based ceramicmaterial and an alkali niobate-based ceramic material.

In the foregoing embodiment, the second protrusions 181 are disposed inthe second valve housing 192. Other forms may also be used. The secondprotrusions 181 may be disposed in the first valve housing 191.

The valve 101 in the foregoing embodiment includes the second sealmember 152, in which the circumference of the first through hole 155A issmaller than that of the first lower valve room 131 and thecircumference of the first through hole 155B is smaller than that of thesecond lower valve room 132 (see FIG. 1). Other forms may also be used.For example, the valve 101 may include a second seal member in which thecircumference of the first through hole 155A is the same as that of thefirst lower valve room 131 and the circumference of the first throughhole 155B is the same as that of the second lower valve room 132.

Similarly, the valve 101 in the foregoing embodiment includes the firstseal member 151, in which the circumference of the second through hole156A is smaller than that of the first upper valve room 133 and thecircumference of the second through hole 156B is smaller than that ofthe second upper valve room 134 (see FIG. 1). Other forms may also beused. For example, the valve 101 may include a first seal member inwhich the circumference of the second through hole 156A is the same asthat of the first upper valve room 133 and the circumference of thesecond through hole 156B is the same as that of the second upper valveroom 134.

Lastly, the description of the above embodiments is to be considered inall respects only as illustrative and not restrictive. The scope of thedisclosure is indicated by the appended claims rather than by theforegoing embodiment. All changes that come within the meaning and rangeof equivalency of the claims are to be embraced within their scope.

REFERENCE SIGNS LIST

S stage

10 piezoelectric pump

40 piezoelectric actuator

41 vibrating plate

43 strengthening plate

45 pump room

51 flexible plate

52 suction hole

53A, 53B, 53C spacer

54 lid plate

55, 56 discharge hole

57 fixed portion

58 movable portion

60 vibrating plate unit

61 frame plate

62 coupling portion

63, 72 external terminal

70 electrode conduction plate

71 frame member

73 internal terminal

80 pump housing

91 base

92 cavity

100 fluid control apparatus

101 valve

106A cuff connection port

109 cuff

109A arm band rubber tube

110, 111 first vent

112 second vent

113 third vent

120 diaphragm

121 hole portion

131 first lower valve room

132 second lower valve room

133 first upper valve room

134 second upper valve room

135 communication path

138, 139 valve seat

140 actuator

151 first seal member

152 second seal member

155A, 155B first through hole

156A, 156B second through hole

160 check valve

170 exhaust valve

180 first protrusion

181 second protrusion

182 cavity

191 first valve housing

192 second valve housing

501 valve

900 fluid control apparatus

901 valve

920 diaphragm

951 first seal member

952 second seal member

1. A fluid control apparatus comprising: a pump having a discharge hole;and a valve comprising: a diaphragm having a hole portion; a first sealmember disposed on a first principal surface of the diaphragm; a firstvalve housing joined to the diaphragm with the first seal memberdisposed therebetween, the first valve housing having a first hole and afirst valve room located near the first principal surface of thediaphragm and communicating with the first hole; a second seal memberdisposed on a second principal surface of the diaphragm; and a secondvalve housing joined to the diaphragm with the second seal memberdisposed therebetween, the second valve housing having a second hole anda second valve room located near the second principal surface of thediaphragm and communicating with the second hole, wherein a surroundingarea of the hole portion in the diaphragm directly contacts the secondvalve housing, and the hole portion is covered therewith, wherein thesecond valve room comprises a valve seat which abuts the surroundingarea of the hole portion in the diaphragm, wherein the surrounding areaof the hole portion in the diaphragm is a portion of the secondprincipal surface of the diaphragm, and wherein the valve seat iscoaxial with the hole portion, wherein the first hole in the first valvehousing is connected to a fluid storage portion that stores fluid,wherein the second hole in the second valve housing is connected to thedischarge hole in the pump, wherein the first valve housing has a thirdhole, and wherein the first principal surface of the diaphragm isconfigured to contact the first valve housing and cover the third hole.2. The fluid control apparatus according to claim 1, wherein each of thefirst seal member, the diaphragm, and the second seal member has aperimeter smaller than a perimeter of each of the first valve housingand the second valve housing.
 3. The fluid control apparatus accordingto claim 1, wherein the second valve housing includes a plurality offirst protrusions located on an outer side portion with respect to thesecond valve room.
 4. The fluid control apparatus according to claim 3,wherein at least one of the first valve housing and the second valvehousing includes a plurality of second protrusions located on an outerside portion with respect to the plurality of first protrusions.
 5. Thefluid control apparatus according to claim 4, wherein the height of eachof the plurality of second protrusions is equal to or greater than a sumof a thickness of the first seal member and a thickness of the secondseal member.
 6. The fluid control apparatus according to claim 1,wherein the first valve housing includes a plurality of cavities locatedin an outer side portion with respect to the first valve room, thesecond valve housing includes a plurality of protrusions located on anouter side portion with respect to the second valve room, the diaphragmis held between the first valve housing and the second valve housingwith the first seal member and the second seal member disposedtherebetween by fitting the plurality of protrusions into the pluralityof cavities.
 7. The fluid control apparatus according to claim 4,wherein each of the plurality of second protrusions has a height smallerthan a height of each of the plurality of first protrusions.
 8. Thefluid control apparatus according to claim 1, wherein the first sealmember has through holes, each having a diameter that is smaller than orequal to a width of the first valve housing.
 9. The fluid controlapparatus according to claim 1, wherein the second seal member hasthrough holes, each having a diameter that is smaller than or equal to awidth of the second valve housing.
 10. The fluid control apparatusaccording to claim 1, wherein the fluid is air.
 11. An apparatus formeasuring blood pressure of a subject including: the fluid controlapparatus according to claim
 1. 12. The fluid control apparatusaccording to claim 4, wherein the height of each of the plurality ofsecond protrusions is equal to a sum of a thickness of the first sealmember, a thickness of the second seal member, and a thickness of thediaphragm.
 13. A fluid control apparatus comprising: a pump having adischarge hole; and a valve comprising: a diaphragm having a holeportion; a first seal member disposed on a first principal surface ofthe diaphragm; a first valve housing joined to the diaphragm with thefirst seal member disposed therebetween, the first valve housing havinga first hole and a first valve room located near the first principalsurface of the diaphragm and communicating with the first hole; a secondseal member disposed on a second principal surface of the diaphragm; anda second valve housing joined to the diaphragm with the second sealmember disposed therebetween, the second valve housing having a secondhole and a second valve room located near the second principal surfaceof the diaphragm and communicating with the second hole, wherein asurrounding area of the hole portion in the diaphragm directly contactsthe second valve housing, and the hole portion is covered therewith,wherein the second valve room comprises a valve seat which abuts thesurrounding area of the hole portion in the diaphragm wherein the valveseat comprises a protrusion extending in a direction towards the secondprincipal surface of the diaphragm, and wherein the valve seat isconfigured to cover the hole portion, wherein the first hole in thefirst valve housing is connected to a fluid storage portion that storesfluid, wherein the second hole in the second valve housing is connectedto the discharge hole in the pump, wherein the first valve housing has athird hole, and wherein the first principal surface of the diaphragm isconfigured to contact the first valve housing and cover the third hole.